The present invention relates to apparatus for separating particles from a fluid flow. Particularly, but not exclusively, the invention relates to apparatus for separating particles, such as dirt and dust particles, from an airflow.
It is well known to separate particles, such as dirt and dust particles, from a fluid flow using a cyclonic separator. Known cyclonic separators are used in vacuum cleaners, for example, and have been known to comprise a low efficiency cyclone for separating fluff and relatively large particles and a high efficiency cyclone located downstream of the low efficiency cyclone for separating the fine particles which remain entrained within the airflow (see, for example, EP 0 042 723B). It is also known to provide, in vacuum cleaning apparatus, an upstream cyclonic separator in combination with a plurality of smaller, downstream cyclonic separators, the downstream cyclonic separators being arranged in parallel wilt one another. An arrangement of this type is shown and described in U.S. Pat. No. 3,425,192 to Davis.
In vacuum cleaner applications, particularly in domestic vacuum cleaner applications, it is desirable for the appliance to be made as compact as possible without compromising the performance of the appliance. It is also desirable for the efficiency of the separation apparatus contained within the appliance to be as efficient as possible (ie. to separate as high a proportion as possible of very fine dust particles from the airflow). It is therefore an object of the present invention to provide improved apparatus for separating particles from a fluid flow. It is a further object of the present invention to provide apparatus for separating particles from a fluid flow having an improved separation efficiency or pressure drop and having a compact arrangement. It is a further object of the invention to provide improved apparatus for separating particles from a fluid flow and suitable for use in a domestic vacuum cleaner.
The invention provides apparatus for separating particles from a fluid flow comprising an upstream cyclonic separator and a plurality of downstream cyclonic separators arranged in parallel with one another, characterised in that each of the downstream cyclonic separators projects, at least in part, into the interior of the upstream cyclonic separator.
The arrangement of the invention makes use of the high separation efficiency achievable by a plurality of parallel cyclones whilst also allowing the combination of the upstream and downstream cyclonic separators to be compactly packaged. This allows the apparatus to be utilised in an appliance such as a domestic vacuum cleaner.
Preferably, each of the downstream cyclonic separators projects into the interior of the upstream cyclonic separator by a distance equal to at least one third of the length of the respective downstream cyclonic separator. More preferably, each of the downstream cyclonic separators projects into the interior of the upstream cyclonic separator by a distance equal to at least half of the length of the respective downstream cyclonic separator. Still more preferably, each of the downstream cyclonic separators projects into the interior of the upstream cyclonic separator by a distance equal to at least two thirds of the length of the respective downstream cyclonic separator. In a preferred embodiment, that each of the downstream cyclonic separators is located substantially wholly within the upstream cyclonic separator. These arrangements give rise to convenient and compact packaging solutions.